Jiaming Lai

Mechanisms and influence of octreotide-induced regulation of somatostatin receptor 2 on hepatocellular carcinoma.

Background: Somatostatin receptors (SSTRs) belong to the family of G protein-coupled receptors. Exposure of G protein-coupled receptors to their agonists induces a rapid decrease in their initial response. The goal of this study is to investigate alteration in SSTR2 by the treatment of SSTR agonist octreotide (OCT) in hepatocellular carcinoma (HCC) and the resulting consequence. Methods: Morphology, proliferation and cell cycle of the human HCC cell line (Bel7402) were evaluated. Effect of OCT on HCC growth and development was assessed in vivo. SSTR2 expression was measured by RT-PCR and detected by immunohistochemistry. Results: Short-term OCT treatment on Bel7402 cells barely changed cell proliferation and morphology, and no apoptosis was induced. The SSTR2 protein level was markedly decreased on Bel7402 cells after exposure to OCT. However, the weight of the HCC xenograft was significantly lower in the OCT treatment group as compared with the control group. In the rat hepatocarcinogenesis model, the mortality and incidence of HCC in the OCT treatment group were remarkably less than those in the control group. Long-term OCT treatment led to increased levels of both SSTR2 mRNA and protein in hepatocytes and HCC cells. Conclusion: Short-term OCT treatment could lead to SSTR2 desensitization, resulting in a reduced inhibitory effect on HCC by OCT. However, long-term OCT treatment effectively inhibited the development and growth of HCC probably via resensitization and upregulation of SSTR2.

Monoamine oxidase A expression is suppressed in human cholangiocarcinoma via coordinated epigenetic and IL-6-driven events

The secretion of dopamine and serotonin is increased in cholangiocarcinoma, which has growth-promoting effects. Monoamine oxidase A (MAOA), the degradation enzyme of serotonin and dopamine, is suppressed in cholangiocarcinoma via an unknown mechanism. The aims of this study were to (i) correlate MAOA immunoreactivity with pathophysiological parameters of cholangiocarcinoma, (ii) determine the mechanism by which MAOA expression is suppressed and (iii) evaluate the consequences of restored MAOA expression in cholangiocarcinoma. MAOA expression was assessed in cholangiocarcinoma and nonmalignant controls. The control of MAOA expression by promoter hypermethylation was evaluated and the contribution of interleukin-6 (IL-6) signaling to the suppression of MAOA expression was determined. The effects of MAOA overexpression on cholangiocarcinoma growth and invasion were also assessed. MAOA expression is correlated with differentiation, invasion and survival in cholangiocarcinoma. The MAOA promoter was hypermethylated immediately upstream of the start codon in cholangiocarcinoma samples and cell lines but not in nonmalignant counterparts. IL-6 signaling also decreased MAOA expression via a mechanism independent of hypermethylation, involving the regulation of the balance between SP-1 transcriptional activity and its inhibitor, R1 repressor. Inhibition of both IL-6 signaling and DNA methylation restored MAOA levels to those observed in cholangiocytes. Forced MAOA overexpression inhibited cholangiocarcinoma growth and invasion. MAOA expression is suppressed by the coordinated control of promoter hypermethylation and IL-6 signaling. MAOA may be a useful prognostic marker in the management of cholangiocarcinoma, and therapies designed to increase MAOA expression might prove beneficial in the treatment of cholangiocarcinoma.

EYA4 functions as tumor suppressor gene and prognostic marker in pancreatic ductal adenocarcinoma through β-catenin/ID2 pathway

Eye absent homolog 4 (EYA4) was initially found as key gene in controlling eye development in Drosophila. We recently found that EYA4 was an independent prognostic factor in hepatocellular carcinoma. Its biological functions in malignancies remained unknown. The present study aimed at investigating its biological functions, molecular mechanisms and prognostic values in pancreatic ductal adenocarcinoma (PDAC). Overexpression of EYA4 in PDAC cells inhibited proliferation and invasion in vitro and tumor growth in vivo. Depletion of EYA4 in PDAC cells enhanced proliferation and invasion in vitro and tumor growth in vivo. Mechanistically, armed with the serine/threonine-specific protein phosphatase activity, EYA4 dephosphorylated β-catenin at Ser675, blocked β-catenin nuclear translocation and inhibited ID2 transactivation. Consistently, EYA4 expression inversely correlated with the levels of p-Ser675-β-catenin and ID2 in tissues. EYA4 expression in PDAC tissues was significantly reduced as compared with adjacent non-tumoral tissues. EYA4 expression was an independent prognostic factor in PDAC, with a lower EYA4 level in association with shorter long-term survival and disease-free time. We showed that EYA4 functioned as tumor suppressor gene in PDAC via repressing β-catenin/ID2 activation, and was an independent prognostic factor in PDAC.

Characterizing the Activation of the Wnt Signaling Pathway in Hilar Cholangiocarcinoma Using a Tissue Microarray Approach

Hilar cholangiocarcinoma (HCCA) is an invasive hepatic malignancy that is difficult to biopsy; therefore, novel markers of HCCA prognosis are needed. Here, the level of canonical Wnt activation in patients with HCCA, intrahepatic cholangiocarcinoma (IHCC), and congenital choledochal cysts (CCC) was compared to understand the role of Wnt signaling in HCCA. Pathology specimens from HCCA (n=129), IHCC (n=31), and CCC (n=45) patients were used to construct tissue microarrays. Wnt2, Wnt3, β-catenin, TCF4, c-Myc, and cyclin D1 were detected by immunohistochemistry. Parallel correlation analysis was used to analyze differences in protein levels between the HCCA, IHCC, and CCC groups. Univariate and multivariate analyses were used to determine independent predictors of successful resection and prognosis in the HCCA group. The protein levels of Wnt2, β-catenin, TCF4, c-Myc, and cyclin D1 were significantly higher in HCCA compared to IHHC or CCC. Wnt signaling activation (Wnt2+, Wnt3+, nuclear β-catenin+, nuclear TCF4+) was significantly greater in HCCA tissues than CCC tissues. Univariable analyses indicated that expression of cyclin D1 as well as Wnt signaling activation, and partial Wnt activation (Wnt2+ or Wnt3+ and nuclear β-catenin+ or nuclear TCF4+) predicted successful resection, but only cyclin D1 expression remained significant in multivariable analyses. Only partial Wnt activation was an independent predictor of survival time. Proteins in the canonical Wnt signaling pathway were present at higher levels in HCCA and correlated with tumor resecility and patient prognosis. These results suggest that Wnt pathway analysis may be a useful marker for clinical outcome in HCCA.

Activation of c-Jun predicts a poor response to sorafenib in hepatocellular carcinoma: Preliminary Clinical Evidence.

We determined the mitogen-activated protein kinase (MAPK) gene expression profile of acquired resistance in sorafenib-sensitive hepatocellular carcinoma (HCC) cells and aimed to identify c-Jun as an important molecule mediating the efficacy of sorafenib. Differences in gene expression of the MAPK signaling between untreated and sorafenib-treated HCC cell lines were investigated using real-time polymerase chain reaction array. Western blot and real-time PCR further evaluated the expression of c-Jun. Pathological specimens from 50 patients with advanced HCC were collected to measure p-c-Jun expression. Sorafenib-resistant HCC cells demonstrated greater levels of basal c-Jun mRNA and protein compared with sorafenib-sensitive HCC cells. Sorafenib activated p-c-Jun in a dose- and time-dependent manner in PLC/PRF/5 and MHCC97H cell lines. Decreased expression levels of 6 genes after sorafenib treatment suggested a robust inhibitory impact of sorafenib on MAPK signaling in HCC cells. c-Jun and p-c-Jun expression levels were inversely correlated with the efficacy of sorafenib; a high expression level of p-c-Jun was associated with resistance to sorafenib and poor overall survival in patients with clinical HCC. p-c-Jun may act as a biomarker for predicting responses of sorafenib treatment, thus advocating targeting of JNK/c-Jun signaling as an optimal therapeutic strategy in a subset of HCC.

WAVE3 Induces EMT and Promotes Migration and Invasion in Intrahepatic Cholangiocarcinoma

AbstractBackground Wiskott–Aldrich syndrome protein family verprolin-homologous protein 3 (WAVE3) plays a critical role in cancer progression and metastasis. However, the specific role of WAVE3 in intrahepatic cholangiocarcinoma (ICC) has not been studied.AimsThis study aimed to explore the role and mechanism of WAVE3 in the progression and metastasis of ICC.MethodsThe expression of WAVE3 in ICC tissues and adjacent non-cancerous tissues was detected by immunohistochemistry. Western blot analysis was utilized to detect the expression of WAVE3 in ICC cells. A transwell assay was used to assess the potential for migration and invasion. The expression of WAVE3 in CC-LP-1 cells was knocked down by small interfering RNA (siRNA) interference.ResultsThe expression of WAVE3 in ICC tissues was significantly higher than that in adjacent non-cancerous tissues. The overall survival was lower in the subgroup of ICC patients with higher WAVE3 expression compared to the subgroup with a lower level of WAVE3 expression. WAVE3 expression was an adverse prognostic factor for ICC patients. CC-LP-1 cells expressed higher levels of WAVE3 protein compared to RBE cells and human intrahepatic biliary epithelial cells, which correlated with greater migration and invasion capabilities compared with the RBE cells. After the transfection of CC-LP-1 cells with WAVE3 siRNA, the level of WAVE3 protein was significantly decreased, accompanied by a marked reduction in migration, invasion and proliferation. Moreover, after the knockdown of WAVE3 expression in CC-LP-1 cells, the protein levels of Slug and Vimentin were significantly decreased, while that of E-cadherin was significantly increased.ConclusionsWAVE3 may represent a new adverse prognostic factor for patients with ICC. This protein enhances migration and invasion capabilities in ICC, most likely through the induction of an epithelial-mesenchymal transition.

WAVE3 promotes proliferation, migration and invasion via the AKT pathway in pancreatic cancer

Alterations in Wiskott-Aldrich syndrome protein family verprolinhomologous protein 3 (WAVE3) expression play various roles in certain types of cancer. However, the roles of WAVE3 expression in pancreatic cancer remain unknown. The present retrospective study demonstrated that WAVE3 expression was higher in cancerous pancreatic tissues than in non-neoplastic tissues. Moreover, WAVE3 overexpression was related to lymphatic metastasis, a poor differentiation and high pre-operative CA19-9 levels and was an adverse prognostic factor for patients with pancreatic cancer. In vitro, the knockdown of WAVE3 inhibited the proliferative, migratory and invasive potential of pancreatic cancer cells and promoted cell apoptosis. Western blot analysis demonstrated that WAVE3 influenced the protein kinase B (PBK/AKT) pathway by suppressing the expression of pyruvate dehydrogenase kinase isoform 2 (PDK2) and then negatively inhibiting the phosphorylation of Ser473 on AKT. Furthermore, the expression of AKT pathway downstream proteins [certain epithelial-mesenchymal transition (EMT)-related proteins, p53, Bcl-2 and cyclin D1] was accordingly altered. Taken together, our findings suggest that WAVE3 influences cell proliferation, migration and invasion via the AKT pathway, and targeting WAVE3 and/or the AKT pathway may potentially serve as a treatment strategy for pancreatic cancer.